Pyrometer.



PATEN'IED JUNE 5, 1906.

E. BENNETT.

PYROMBTER.

APPLICATION FILED 0GT.2'1,1900.

Rig. 2.

Rig. 4.

WITNESSES.-

Afro/ME).

UNITED s ArEs PATENT orrron.

EDWARD BENNETT,,OF PITTSBURG, PENNSYLVANIA, ASSIGN OR TO GEORGE WESTINGHOUSE, 'OF PITTSBURG, PENNSYLVANIA.

PYROMETEFI- Specification of Letters Patent.

.Eatented June 5, 1906.

To all whom it may concern:

Be it known that I, EDWARD BENNETT, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented new and useful Improvements in Pyrometers, of which the following is a specification.

My invention relates to pyrometers and it has for its object to provide a device of this character which shall be simple and inexpensive in construction and reliable in operation and which may be employed for accurately measuring higher temperatures than has been possible with devices of this general character heretofore employed.

My invention is primarily based upon the well-known fact that the ohmic resistance of 'all materials is a function of temperature; but my invention differs radically from those heretofore employed which have utilized this principle by reason of the material ofwhich it is composed and its general characteristics of structure and the wide range of temperatures, the measurement of which it may be used to accurately determine.

In the drawings illustrating the invention, Figure 1 is a view, partially in side elevation and partially in section, of the resistance body or filament of the pyrometer, showing one means of attaching the terminal leads thereto. Fig. 2 is a sectional view of another form of the resistance-body, showing another means of attaching the terminal leads. Fig. 3 is a diagram of t e circuits employed in the calibration of the resistance body or filament. Fig. 4 is a sectional view of one means of mounting and utilizing the filament, and Figs. 5 and 6 are respectively a sectional view and a side elevation of two other means of mounting the filament. Fig. 7 is a view, partially in elevation and partially in section of a modified form of the invention.

The resistance body or filament 1 is composed of one or more of the refractory stable oxidssuch, for example, as zirconia and yttria, which have negative temperature coefiicients and are non-conductors at ordinary temperatures. The material of which the filament is to be composed is ground to a fine powder, and enough organic binder and water are added to make a stiff clay-like substance, which is forced under heavy pressure through a suitable die into the form of a long rod or "string. After drying, the strlng is slowly heated to a high temperature in a furnace, thus burning out the organic binder and leaving a hard compact body. After the roasting is completed the string is provided with terminal leads, which are 'then connected .to an electric circuit, and the string is heated to a conducting temperature by some external means if it be a non-conductor at ordinary temperatures. Sufiicient current is then passed through it to keep it or maintain it in an incandescent condition for a considerable length of time, its temperature being raised and maintained to a point above the highest temperature to which it will ever be subjected when used as a pyrometer in order that the material may be thoroughly shrunk, and any changes which might take place gradually in use may be brought about in a short time, so that all subsequent heating and cooling will'only subject the material to the same changes as' those to which it has already been subjected.

After being subjected to the treatment just described the string is cutup into the required lengths, and each length is provided with terminal leads, usually of platinum wire 2. These lead-wires may be fastened to the ends of the filament or rod 1 in any suitable manneras, for example, by wind ing them about the ends of the filament and applying a coating 3 of paste composed of like or similar material to that of the body of the filament and then baking the paste, so as to harden it and fasten the lead-wires securely in position.

Another method of attaching the leadwires 2 is indicated in Fig. 2, this method being set forth nra patent granted to Marshall W. Hanks, June 26, 1900, No. 652,607. The calibration of the filament may be effected by connecting it in the circuit, as indicated in Fig. 3, in which the source of current 4, here indicated as a battery, is employed in connection with a voltmeter 5' and a switch 6, the switch being provided with two stationary contact-termmals, so that the switch-arm may be first moved into posi tion to determine the voltage of the source of the current and then into contact with the other terminal to place the filament 1 in circuit with the source of current and the voltmeter.

In Fig. 4 the filament is shown as inclosed open at both ends, and the tube 7 is inclosed in a second tube 8, of refractory material, having one end closed. One of the lead-wires 2.

projects out through the inner tube, and the other lead-wire projects out between the walls of the two tubes 7 and 8. This arrangement of apparatus is such as to effectually protect the filament frominjury and also lnsure its proper subjection to the temperature that. it is desired to measure.

In Fig. 5 I have shown the filament as mounted within a single tube 9 of refractory.

material, both ends of which are closed. In

, Fig. 6 the filament is su orted u on a late PE P P or stri 10 by means of t e lead-wires 2. I

In 1g. 7 the filament'l is shown as curved and as provlded withleads 11, formed of a material such, for example, as graphithaving low' ohmic resistance, but having a meltingpoint above that of latinum, this con struction being employe in cases where the temperatures to be measured lie above the melting-point of platinum.

The materials, employed in making the pyrometer-filaments may be varied largely .to suit the convenience or Wishes of the manufacturer, since there are man refractory stable oxids that are suitable or this pur-' The character of these filaments is pose. such that. tem eratures much above the melting-point o metals may be accurately measured, and the range of such high temcemented to the ends t ereof, and a protecting devicefor said body.

2. A pyrometer comprising an elongated, cylindrical resistance-body composed of one or more of the stable, refractory oxids and being a non-conductor of electricit when cold and a conductor when hot, re atively low resistance, refractory terminal conductors cemented to its ends, and supporting ind protecting means for said resistanceody.

3 A pyrometer comprising an elongated resistance-body that is composed of one or more of the stable, refractory oxids; that is a non-conductor of electricity when cold, relatively low resistance, refractory terminal leads cemented to its ends and a tube of refractory material inclosing and supporting said resistance-body.

4. A pyrometer comprising an elongated resistance-body that is composed of one or more of the stable, refractory oxids, that is a' non-conductor of electricity when cold, relatively low resistance, refractory terminal leads cemented to' its ends, a tube in which .said body is located and a larger tube surrounding the first-named tube.

5. A pyrometer comprisin two tubes of refractory material, the one wlthin the other, and a resistance-bod composed of one or 'more of the stable, re actory oxids of metals and having a negative temperature coefficient, and refractory, terminal leads which are respectively located Within the inner tube and between the tubes.

6; .A pyrometer comprising an elongated resistance-body of refractory material having a negative temperature coefi icient and relatively low resistance, refractory terminal conductors cemented to its ends and two refractory tubes, the one within the other for protecting the refractory body and separating the terminal leads from each other. i

In testimony whereof I have hereunto subscribed my name this 19th day of October, 1900. 4

. EDWARD BENNETT. Witnesses:

MURRAY 0. BEEBE,

HUGH ApOsooxs. 

